Dud 


DIAGNOSES  OF  NEW-  SPECIES  OF  MARINE  BIVALVE 
MOLLUSKS  FROM  THE  NORTHWEST  COAST  OF 
AMERICA  IN  THE  COLLECTION  OF  THE 
UNITED  STATES  NATIONAL  MUSEUM 

THt  LitfRARY 

OF  [HE 

UNIVERSITY  OF  ILLINOIS 

WILLIAM  HEALEY  DALL 

Honorary  Curator  of  Mollusks,  United  States  National  Museum 


No.  2183. — From  the  Proceedings  of  the  United  States  National  Museum, 
Vol.  52,  pages  393-417 

Published  December  27,  1916 


Washington 

Government  Printing  Office 
1916 


DIAGNOSES  OF  NEW  SPECIES  OF  MARINE  BIVALVE 
MOLLUSKS  FROM  THE  NORTHWEST  COAST  OF 
AMERICA  IN  THE  COLLECTION  OF  THE 
UNITED  STATES  NATIONAL  MUSEUM 


BY 

WILLIAM  HEALEY  DALL 


Honorary  Curator  of  Mollusks,  United  States  National  Museum 


No.  2183. — From  the  Proceedings  of  the  United  States  National  Museum, 
Vol.  52,  pages  393-417 

Published  December  27,  1916 


Washington 

Government  Printing  Office 
1916 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/diagnosesofnewspOOdall 


DIAGNOSES  OF  NEW  SPECIES  OF  MARINE  BIVALVE  MOL- 
LUSKS  FROM  THE  NORTHWEST  COAST  OF  AMERICA  IN 
THE  COLLECTION  OF  THE  UNITED  STATES  NATIONAL 
MUSEUM. 


By  William  Healey  Dall, 

Honorary  Curator  of  Mollusks,  United  States  National  Museum. 


Having  in  preparation  a check  list  of  the  bivalve  mollusks  con- 
tained in  the  marine  fauna  of  the  region  including  the  coasts  from 
Point  Barrow  in  the  Arctic  to  San  Diego,  California,  it  was  found 
that  a comparatively  large  number  of  the  species  in  the  collection 
of  the  United  States  National  Museum  were  undescribed. 

To  avoid  launching  into  the  literature  a quantity  of  manuscript 
names  the  present  diagnoses  have  been  prepared.  It  is  hoped  at  no 
very  distant  date  to  furnish  fuller  data  concerning  these  species,  in- 
cluding suitable  figures. 

In  the  descriptive  matter  following,  when  a station  number  is  given 
it  refers  always  to  the  number  of  a dredging  station  of  the  United 
States  Fisheries  Steamer  Albatross.  The  data  relating  to  these  sta- 
tions have  been  printed  by  the  Bureau  in  its  Bulletins.  Those  species 
not  referred  to  a station  number  were  collected  by  private  persons, 
including  the  writer,  at  various  times  during  the  last  sixty-five  years, 
one  species  having  been  picked  up  by  Major  Rich  during  the  Mexican 
War. 

The  typical  specimens  are  all  preserved  in  the  collection  of  the 
United  States  National  Museum.  Had  the  undescribed  species  be- 
longing to  the  more  southern  fauna  now  in  the  collection  been  in- 
cluded, the  number  would  certainly  have  been  greatly  increased. 
These  forms,  however,  are  reserved  for  treatment  later. 

In  the  descriptions  when  the  beaks  are  said  to  be  a certain  distance 
behind  the  end  of  the  shell,  the  distance  is  measured  from  a vertical 
line  dropped  from  the  umbo  to  the  basal  margin,  and  at  the  level  of 
the  most  distant  point  of  the  end  of  the  shell  referred  to.  This  vertical 
line  indicates  the  height,  the  length  being  measured  on  a horizontal 
line  parallel  with  the  base  of  the  shell  in  a general  sense.  The  diame- 
ter is  the  maximum  distance  from  the  outside  of  one  valve  to  the  out- 
side of  the  other,  taken  at  right  angles  to  the  vertical  plane  of  the 
valves.  Measurements  are  all  in  millimeters. 

Proceedings  U.  S.  National  Museum,  Vol.  52— No.  2183. 


p499:i  0 


393 


394 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


NUCULA  CARDARA,  new  species. 

Shell  polished,  light  olive-green,  thin,  elongate-oval,  with  8 anterior 
and  18  posterior  prominent  teeth,  the  resilifer  prominent  and  largely 
free  from  the  hingeline,  the  interior  very  pearly,  the  valve-margin 
smooth,  the  beaks  hardly  prominent,  situated  5 mm.  behind  the 
anterior  end  of  the  shell  and  showing  the  whitish  prodissoconch. 
Length,  16;  height,  11.5;  diameter,  8 mm.  Cat.  No.  265905,  U.S.N.M. 

Station  5673,  in  1090  fathoms,  mud,  off  San  Diego,  California. 

This  elegant  shell  has  no  sculpture  except  incremental  lines  which 
are  hardly  visible,  hut  toward  the  margin  become  strong  at  intervals, 
but  without  regularity.  The  periostracum  near  the  beaks  becomes 
dark,  and  in  the  closed  shell  suggests  Mdlletia.  There  is  no  lunular 
boundary  around  the  subumbonal  depression. 

NUCULA  DARELLA,  new  species. 

Shell  small,  inflated,  sub  triangular,  the  anterior  end  slightly  shorter; 
periostracum  dark  olive,  the  surface  smooth  except  for  somewhat 
irregular,  inconspicuous  incremental  lines,  but  under  a lens  showing 
faint  close  radial  striae;  lunule  large,  distinctly  limited  by  an  im- 
pressed line,  mesially  with  a slight  pout;  about  five  anterior  and  eight 
posterior  hinge  teeth,  the  resilifer  deep,  small,  central,  not  projecting; 
inner  margins  of  the  valves  sharply  radially  grooved;  beaks  pointed, 
showing  the  prodissoconch  plainly.  Length,  4 ; height,  3 ; diameter, 
2.7  mm.  Cat.  No.  111424,  U.S.N.M. 

Station  2923,  822  fathoms,  off  San  Diego,  California. 

NUCULA  LINKI,  new  species. 

Shell  small,  inflated,  smooth,  dark  olive,  very  inequilateral,  sub- 
triangular,  the  anterior  end  shorter;  lunule  large,  bounded  by  a faint 
keel;  beaks  prominent  showing  the  whitish  prodissoconch;  six  an- 
terior and  eleven  posterior  hinge  teeth;  valve-margin  entire;  the 
resilifer  small,  deeply  set,  subumbonal,  not  projecting.  Length,  6; 
height,  5;  diameter,  3.6  mm.  Cat.  No.  107649,  U.S.N.M. 

Station  3034, 24  fathoms,  mud  ; off  Point  Fermin,  Lower  California. 

NUCULA  QUIRICA,  new  species. 

Shell  small,  dark  olive  inclining  to  black,  polished,  with  rather  rude 
irregular  incremental  lines;  rounded  triangular,  the  anterior  end  very 
short;  valves  inflated  with  seven  anterior  and  twelve  posterior  hinge- 
teeth,  the  resilifer  narrow,  elongated,  very  oblique,  almost  parallel 
with  the  posterior  dorsal  margin,  hardly  projecting;  inner  margin  of 
the  valves  entire;  beaks  prominent  showing  the  prodissoconch, 
lunule  obscure.  Length,  8;  height,  6;  diameter,  3.5  mm.  Cat.  No. 
208727,  U.S.N.M. 

Chugachik  Bay,  Cooks  Inlet,  Alaska,  in  60  fathoms,  gravelly 
bottom. 


no.  2183. 


NEW  NORTHWEST  AMERICAN  BJ  VALVES— D ALL. 


395 


NUCULA  PETRIOLA,  new  species. 

Shell  minute,  ovate,  inflated,  the  form  resembling  Crenella  Colum- 
biana, the  prodissoconoh  visible  on  the  rather  inflated  beaks;  lunule 
obscure;  color  greenish  olive,  smooth  and  polished;  valve  margins 
smooth,  hinge  line  very  short.  Length,  1.25;  height,  2;  diameter, 

I. 5  mm.  Cat.  No.  271416,  U.S.N.M. 

Off  Santa  Rosa  Island,  California,  in  53  fathoms,  mud.  The  solid 
shell  and  inflated  form  of  this  minute  Nucula  seem  to  indicate  that  it 
is  not  an  immature  shell. 

LEDA  NAVISA,  new  species. 

Shell  elongate,  arcuate,  inequilateral,  with  slender  recurved  rostrum 
and  well-marked  smooth  impressed  escutcheon  but  no  lunule;  base 
convexly  arcuate,  rostrum  obliquely  truncate,  anterior  end  evenly 
rounded;  beaks  obscure,  5.5  mm.  from  the  anterior  end;  sculpture  of 
numerous  sharp  concentric  low  ridges,  with  wider  flat  interspaces, 
obsolete  toward  the  rostrum;  anterior  teeth  about  twelve,  posterior 
about  twenty,  the  resilifer  minute,  subumbonal,  not  projecting; 
interior  chalky,  a small  medial  ridge  near  the  end  of  the  rostrum. 
Height,  7;  length,  16;  diameter,  5 mm.  Cat.  No.  208770,  U.S.N.M. 

Off  the  Farallones  Islands,  California,  in  191  fathoms,  sand;  bottom 
temperature  44°.  5. 

LEDA  AMIATA,  new  species. 

Shell  light  olivaceous,  elongate,  compressed,  the  posterior  dorsal 
margin  nearly  straight;  beaks  low,  polished,  about  3.5  mm.  from 
the  anterior  end,  showing  the  whitish  prodissoconch;  the  smooth  sur- 
face continues  for  a short  distance  when  the  sculpture  changes  to 
sharply  evenly  lamellose  with  slightly  larger  interspaces  wider  on  the 
rostral  area  which  is  defined  by  the  angular  turn  of  the  lamellae 
which  stop  short  at  the  sharp  margin  of  the  long  impressed  escutcheon; 
interior  porcellanous,  with  twelve  anterior  and  sixteen  posterior 
teeth,  the  resilifer  minute,  subumbonal,  hardly  projecting.  Length, 

II. 3;  height,  4.5;  diameter,  3.0  mm.  Cat.  No.  209252,  U.S.N.M. 

Station  4351,  off  San  Diego,  California,  in  488  fathoms,  muddy  bot- 
tom. This  elegant  shell  recalls  L.  constellata  of  the  Panama  fauna, 
but  the  rostrum  is  more  simply  sculptured. 

LEDA  OXIA,  new  species. 

Shell  minute,  rounded  in  front,  very  acute  behind,  the  valve  end- 
ing in  a sharp  point;  base  arcuate,  beaks  low,  subcentral,  dorsal 
slopes  nearly  straight;  sculpture  of  regular,  equal  concentric  ridges 
with  subequal  interspaces,  a depressed  ray  from  the  beak  to  the  base 
anteriorly,  a deeply  impressed,  concentrically  striated  escutcheon 
bordered  by  a rounded  keel;  lunule  linear;  about  eight  teeth  on  either 


396 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol  5: 


side  of  a minute  resilifer.  Length,  4.5;  height,  3;  diameter,  1 mm. 
Cat.  No.  214448,  U.S.N.M. 

Station  2901,  off  Santa  Rosa  Island,  California,  in  48  fathoms, 
muddy  bottom.  This  species  is  related  to  L.  commutata. 

LEDA  LIOGONA,  new  species. 

Shell  small,  light  yellowish,  concentrically  sculptured  with  prom- 
inent elevated  ridges  with  wider  interspaces,  except  on  the  beaks 
where  the  prodissoconch  is  relatively  large  and  perfectly  smooth,  the 
concentric  sculpture  commencing  abruptly;  beaks  low,  and  about  3 
mm.  from  the  anterior  end;  base  slightly  arcuate,  dorsal  slopes  direct, 
rostrum  abruptly  truncate;  posterior  dorsal  area  with  two  obscurely 
elevated  rays  over  which  the  concentric  sculpture  is  higher,  but  it 
becomes  reduced  to  striation  upon  the  strongly  impressed  escutcheon; 
teeth  much  crowded,  about  twelve  posterior  and  about  the  same  num- 
ber in  front  of  the  minute  subumbonal  resilifer.  Length,  9;  height, 
5.3;  diameter,  3.3  mm.  Cat.  No.  214089,  U.S.N.M. 

Station  3604,  Bering  Sea,  in  1401  fathoms,  mud. 

This  species  differs  from  the  young  of  L.  radiata  Krause,  by  its  more 
conspicuous  and  regular  sculpture  and  by  the  absence  of  radiating 
threads.  It  probably  attains  a larger  size. 

LEDA  FOSSA  Baird,  1863. 

Variety  sculpta  Dali.  This  form  has  regular  concentrio  ripples  on 
the  beaks,  behind  a faint  depressed  ray  near  the  anterior  end  and  on 
the  keels  on  either  side  of  the  escutcheon.  Cat.  No.  107688,  U.S.N.M. 

Station  2855,  southeast  of  Alaska  Peninsula,  in  66  fathoms,  mud. 

Variety  vaginata  Dali.  This  differs  from  the  last  in  having  the 
concentric  sculpture  finer  and  less  evident,  and  spread  over  the  entire 
shell.  Cat.  No.  226072,  U.S.N.M. 

Station  4244,  at  Kasa-an  Bay,  Alaska,  in  50  fathoms,  mud. 

Variety  curtulosa  Dali.  Shell  resembling  variety  sculpta  but  rela- 
tively shorter  than  that  or  the  typical  form.  Cat.  No.  33771,  U.S.N.M. 

Unalaska  Harbor  in  60  fathoms  on  the  Ridge. 

LEDA  GOMPHOIDEA,  new  species. 

Shell  elongate,  inequilateral,  smooth,  polished,  the  rostrum  ob- 
liquely rounded-truncate,  the  anterior  side  rounded  and  shorter; 
beaks  small,  but  pustule  like,  5 mm.  from  the  anterior  end,  the  prodis- 
soconoh  distinct;  teeth  small  and  numerous,  about  25  in  front  of  and 
35  behind  the  small  oblique  resilifer;  posterior  basal  and  dorsal  mar- 
gins nearly  straight,  the  escutcheon  narrow,  long,  impressed,  and 
striated.  Length,  17.5;  height,  8;  diameter,  4 mm.  Cat.  No. 
212889,  U.S.N.M. 

Station  3346,  off  Tillamook  Bay,  Oregon,  in  786  fathoms. 


no.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— D ALL. 


397 


LEDA  FIASCONA,  new  species. 

Shell  small,  sub  triangular,  rounded,  thin,  dull  olive,  the  anterior 
slightly  shorter  than  the  posterior  end,  the  base  arcuate;  the  posterior 
end  attenuated,  compressed,  pointed;  sculpture  of  fine  concentric 
threads,  close  set  and  covering  the  anterior  two-thirds  of  the  valves, 
stopping  abruptly  at  the  posterior  third  where  the  compression 
begins;  beaks  not  prominent,  a small  and  narrow  lunule  and  escutch- 
eon indicated;  hinge  with  8 anterior  and  about  4 posterior  teeth, 
the  resilifer  small,  subumbonal,  not  projecting.  Length,  4;  height, 
2.7;  diameter,  1.7  mm.  Cat.  No.  215597,  U.S.N.M. 

Station  2923,  off  San  Diego,  in  822  fathoms,  mud. 

LEDA  PHENAXIA,  new  species. 

Shell  small,  solid,  plump,  smooth  except  for  faintly  evident  incre- 
mental fines  and  delicate  radial  striulae;  periostracum  dark  olive, 
immediately  under  the  beaks  blackish  for  a short  distance;  base 
evenly  arcuate,  dorsal  slopes  nearly  straight;  beaks  nearer  the  ante- 
rior end,  full,  not  pointed,  with  a short-cordate  lunular  impression  and 
narrow,  elongate  escutcheon,  neither  defined  by  any  sharp  boundary; 
hinge  very  strong  for  the  size  of  the  shell,  with  about  8 or  9 long  teeth 
on  each  side  of  a rather  small  strong  resilifer.  Length,  4.5;  height, 
3.5;  diameter,  1.3  mm.  Cat.  No.  215596,  U.S.N.M. 

Station  2923,  off  San  Diego,  California,  822  fathoms,  mud. 

The  short  blackish  patch  of  periostracum  directly  between  the 
beaks  gives  this  little  shell  the  aspect  of  a Tindaridj  and  the  strong 
hinge  makes  the  shell  very  difficult  to  open,  but  the  ligament  is 
strictly  internal. 

LEDA  SPARGANA,  new  species. 

Shell  small,  elongate,  inequilateral,  pale  olivaceous,  compressed; 
prodissoconch  conspicuous,  otherwise  the  beaks  are  low,  and  about 
4 mm.  from  the  anterior  end  of  the  shell;  sculpture  of  low  concentric 
ridges,  stronger  anteriorly,  sparser  toward  the  beaks,  and  obsolete  on 
the  dorsal  area  behind;  there  is  an  obscure  radial  depression  ante- 
riorly, and  two  obscure  radial  ridges  on  each  side  of  the  impressed 
escutcheon  where  the  dorsal  margin  of  the  valves  is  prominently  ele- 
vated; there  are  about  12  anterior  and  18  posterior  teeth,  the  resilifer 
is  small,  rotund,  and  subumbonal;  there  is  a small  mesial  ridge  near 
the  end  of  the  rostrum  internally.  Length,  12;  height,  5;  diameter, 
2.6  mm.  Cat.  No.  208897,  U.S.N.M. 

Station  4367,  off  Point  Loma,  San  Diego  County,  California,  in  215 
fathoms,  mud. 

LEDA  HAMATA  Carpenter,  1864. 

Variety  limata  Dali.  In  this  variety  the  valves  have  the  same  pro- 
file as  in  the  typical  form  but  the  strong  concentric  sculpture,  which  is 
so  uniform  in  the  northern  specimens  of  this  species,  is  subject  to 


398 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


extraordinary  mutations,  which  taken  alone  would  appear  to  represent 
perfectly  distinct  species.  In  the  extreme  form  of  this  variety  the 
surface  of  the  disk  is  perfectly  smooth.  In  another  mutation  there 
are  a few  very  coarse  concentric  ridges  near  the  umbones.  In  still 
another  the  umbonal  region  is  smooth  and  the  ridges  appear  near  the 
basal  margin  only.  The  keels  on  the  rostrum  in  typical  limata  are 
plain,  in  other  specimens  there  may  be  successive  prominent  concen- 
tric ridges  rising  into  pustules  where  they  intersect  the  keels.  Almost 
every  combination  of  these  characters  may  be  found  in  a large  series 
of  the  species.  These  fluctuations  appear  to  be  connected  with  the 
southern  habitat,  being  most  violent  in  specimens  collected  at  La  Paz, 
just  inside  the  Gulf  of  California.  A somewhat  similar  series  of  mu- 
tations has  been  noticed  in  one  of  the  species  from  the  Miocene  of 
Virginia.  Cat.  No.  211292,  U.S.N.M. 

Station  (of  the  typical  specimens)  2902,  off  Santa  Rosa  Island, 
California,  in  50  fathoms. 

YOLDIA  OLEACINA,  new  species. 

Shell  small,  plump,  smooth  except  for  faint  incremental  lines,  bril- 
liantly polished,  of  a bright  yellow  brown  with  a slight  olivaceous 
tint  toward  the  beaks;  egg-ovate,  rounded  and  broader  in  front, 
attenuated  behind;  base  broadly  arcuate,  dorsal  margin  gently 
curved;  beaks  low,  6 mm.  from  the  anterior  end;  no  defined  lunule 
or  escutcheon;  13  anterior  and  11  posterior  hinge  teeth,  the  resilifer 
subumbonal,  cup-like;  the  pallial  line  has  a slight  shallow  sinus  near 
the  posterior  adductor  scar.  Length,  16;  height,  9;  diameter,  6 mm. 
Cat.  No.  223407,  U.S.N.M. 

Arctic  Ocean  north  of  Bering  Strait,  Captain  Healy. 

This  brillant  species  recalls  several  of  the  Arctic  species,  but  does 
not  exactly  agree  with  any  of  them. 

YOLDIA  SECUNDA,  new  species. 

Shell  large,  thin,  inequilateral,  inflated,  subtruncate  and  recurved 
behind;  color  of  a light  grayish  olive,  more  or  less  disposed  in  zones; 
this  shell  much  resembles  Y.  thraciaeformis  Storer,  though  it  does 
not  attain  so  great  a size;  it  differs  by  the  absence  of  the  oblique  ele- 
vated posterior  ray  from  the  umbones,  in  being  more  attenuated 
behind,  and  in  general  more  cylindrically  inflated;  the  valves  hardly 
gape  in  front,  and  less  behind  than  in  that  species;  the  hinge  teeth 
are  more  numerous  and  smaller  than  in  thraciaeformis  of  the  same 
length.  There  are  24  anterior  and  20  posterior  teeth,  the  resilifer  is 
similar  to  but  smaller  than  in  the  species  referred  to  above,  which 
has  20  anterior  and  10  posterior  teeth  in  a valve  of  the  same 
length.  Length,  39;  height,  22;  diameter,  14  mm.  (Cat.  No.  107688, 
U.S.N.M.) 

Station  3077,  in  Clarence  Strait,  Alaska,  in  322  fathoms,  mud. 


no.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— D ALL. 


399 


YOLDIA  BERINGIANA,  new  species. 

Shell  large,  thin,  smooth,  except  for  lines  of  growth,  brilliantly 
polished,  inequilateral,  hardly  rostrate,  rounded  at  each  end,  less 
compressed  behind  than  Y.  secunda ; color  a rich  yellowish  brown? 
slightly  olivaceous  near  the  umbones;  valves  closing  completely; 
escutcheon  striated,  narrower  than  in  secunda;  beaks  very  low,  24 
anterior  and  17  posterior  teeth,  the  resilifer  ample,  cup-shaped,  pro- 
jecting. The  pallial  sinus  is  rather  large  and  rounded.  Length,  40; 
height,  22;  diameter,  16  mm.  Cat.  No.  226195,  U.S.N.M. 

Station  3607,  Bering  Sea,  off  the  Pribiloff  Islands,  in  987  fathoms, 
mud. 


YOLDIA  ORCIA,  new  species. 

Shell  small,  thin,  pale  olive,  brilliantly  polished,  smooth,  equilat- 
eral; base  deeply  arcuate;  beaks  not  prominent,  the  posterior  end 
slightly  compressed,  pointed  and  attenuated,  the  anterior  end  rounded; 
hinge  with  8 anterior  and  6 very  minute  posterior  teeth,  the  resilifer 
subumbonal,  extremely  small.  Length,  4.5;  height,  3.5;  diameter 
2 mm.  Cat.  No.  111420,  U.S.N.M. 

Station  2923,  off  San  Diego,  California,  in  822  fathoms,  mud. 

This  species  has  no  indication  of  lunule  or  escutcheon. 

YOLDIA  SANESIA,  new  species. 

Shell  small,  thin,  plump,  pale  olivaceous,  inequilateral,  the  anterior 
end  shorter,  the  beaks  2.6  mm.  behind  it;  base  roundly  arcuate,  dorsal 
slopes  nearly  straight,  anterior  end  rounded,  posterior  end  slightly 
recurved,  compressed  and  bluntly  rounded;  beaks  low,  inconspicuous, 
with  no  indications  of  lunule  or  escutcheon;  hinge  with  7 or  8 very 
minute  anterior  and  about  10  posterior  teeth,  the  resilifer  subumbonal 
and  minute.  Length,  6;  height,  4;  diameter,  2.5  mm.  Cat.  No. 
223578,  U.S.N.M. 

Station  4224,  in  Boca  de  Quadra,  Alaska,  in  160  f thorns,  mud. 

YOLDIA  CECINELLA,  new  species. 

Shell  minute,  polished,  smooth,  nearly  equilateral,  the  margins 
arcuate  above  and  below,  the  anterior  end  rounded,  the  posterior  more 
pointed  and  slightly  longer;  beaks  low  and  inconspicuous,  with  neither 
lunule  nor  escutcheon  indicated;  hinge  with  six  or  seven  minute  teeth 
on  each  side  of  the  subumbonal,  very  small  resilifer.  Length,  5; 
height,  2.6;  diameter,  1.5  mm.  Cat.  No.  211424,  U.S.N.M. 

Station  2823,  off  La  Paz,  Gulf  of  California,  in  about  26  fathoms. 

This  species  is  quite  close  to  Y.  orcia , but  is  uniformly  less  acute 
behind,  smaller  and  more  slender. 


400 


PROCEEDINGS  OF  TEE  NATIONAL  MUSEUM. 


vol.  52. 


YOLDIA  CAPSA,  new  species. 

Shell  very  thin,  small,  polished,  smooth,  compressed,  the  beaks 
hardly  rising  above  the  general  hingeline;  base  deeply  arcuate,  the 
dorsal  margin  very  slightly  convex;  anterior  end  rounded,  posterior 
end  slightly  broader  and  flatter,  obscurely  pointed  toward  the  dorsal 
level;  beaks  slightly  anterior  to  the  middle  line  of  the  shell;  hinge 
with  a few  very  small  anterior  and  posterior  teeth;  the  resilifer  sub- 
umbonal,  not  projecting.  Length,  4.4;  height,  3;  diameter,  1.5  mm. 
Cat.  No.  212499,  U.S.N.M. 

Station  3346,  off  Tillamook  Bay,  Oregon,  in  786  fathoms. 

MALLETIA  (MINORMALLETIA)  TALAMA,  new  species. 

Shell  large,  thin,  plump,  of  a uniform  oval,  with  a brilliant,  smooth, 
light  yellowish-olive  periostracum;  beaks  low,  near  the  anterior  third 
with  about  eight  V-shaped  teeth  in  front  of  them  on  the  hingeline 
and  about  36  much  smaller  teeth  behind  them;  the  latter  are  not 
obviously  V-shaped,  are  very  uniform  in  size  and  appearance;  the 
hingeline  is  thickened  under  the  anterior  teeth,  but  the  ligament  is 
strictly  external.  The  shell  is  slightly  wider  and  more  compressed 
behind  the  beaks  but  the  difference  is  very  small.  Length,  23; 
height,  15;  diameter,  10  mm.  Cat.  No.  225384,  U.S.N.M. 

Station  3603,  off  Pribiloff  Islands,  Bering  Sea,  in  1771  fathoms. 

MALLETIA  (NEILO)  FIORA,  new  species. 

Shell  small,  thin,  inequilateral,  smooth,  polished,  pale  olivaceous, 
somewhat  compressed,  the  beaks  at  4 mm.  behind  the  anterior 
rounded  end;  the  base  evenly  arcuate,  the  dorsal  slopes  nearly 
straight;  near  the  posterior  end  the  profile  is  obliquely  attenuated 
above  and  below,  terminating  in  a point;  ligament  distinctly  external 
with  about  ten  anterior  and  more  numerous  posterior  teeth.  Length, 
10.5;  height,  5.5;  diameter,  3 mm.  Cat.  No.  207251,  U.S.N.M. 

Station  2859,  southwest  of  Sitka  Bay,  Alaska,  in  1,569  fathoms. 

TINDARIA  CALIFORNICA,  new  species. 

Shell  small,  olivaceous,  darker  distally,  inflated,  smooth  except  for 
incremental  lines,  polished,  swollen,  inequilateral;  beaks  inconspic- 
uous, with  a large  escutcheon  bounded  by  an  angle  of  the  surface,  but 
no  lunule;  anterior  end  rounded,  plump,  4 mm.  in  front  of  the  beaks; 
posterior  end  attenuated,  bluntly  rounded,  and  slightly  recurved, 
the  posterior  dorsal  slope  being  somewhat  concave;  the  base  evenly 
arched;  hinge  with  13  anterior  and  18  posterior  teeth;  ligament 
strictly  external,  pallial  sinus  deep.  Length,  10.5;  height,  6;  diam- 
eter, 4.5  mm.  Cat.  No.  96972,  U.S.N.M. 

Station  2840,  off  the  Santa  Barbara  Islands,  California,  in  276 
fathoms,  mud. 


so.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— BALL. 


401 


TINDARIA  BRUNNEA,  new  species. 

Shell  small,  inflated,  solid,  sub  triangular,  of  a warm  yellow  brown 
color;  beaks  large,  prominent,  with  no  distinguishable  lunule  or 
escutcheon,  the  ligament  short  but  wholly  external  and  behind  the 
beaks;  the  surface  sculptured  with  rather  regular  fine  incremental 
lines  which,  toward  the  margin,  appear  almost  like  concentric  ripples ; 
there  are  also  very  faint  radial  lines  on  some  parts  of  the  shell;  base 
arcuate,  dorsal  slopes  nearly  straight,  anterior  end  rounded,  posterior 
rather  bluntly  pointed;  hinge  with  about  eight  anterior  and  fourteen 
posterior  teeth.  Length,  7.5;  height,  6;  diameter,  4 mm.  Cat.  No. 
226333,  U.S.N.M. 

Station  3604,  Bering  Sea,  in  1,401  fathoms. 

The  bright  color  distinguishes  this  from  the  other  species  at  a 
glance. 

TINDARIA  MARTINIANA,  new  species. 

Shell  small,  solid,  olivaceous,  inflated,  subtriangular,  inequilateral, 
the  beaks  nearer  the  anterior  end;  sculpture  of  fine  concentric  and 
still  finer  radial  striae  only  visible  under  magnification;  beaks  full, 
incurved,  3.5  mm.  from  the  anterior  end,  a small  lanceolate  lunule 
and  a narrower  and  longer  escutcheon  are  indicated  only  by  the  brown 
color  of  their  areas  against  the  pale  olive  of  the  shell;  shell  rounded  in 
front,  pointed  bluntly  behind,  the  base  arcuate,  the  dorsal  slopes 
nearly  straight;  hinge  with  14  anterior  and  16  posterior  slender  teeth, 
the  ligament  entirely  external  and  posterior.  Length,  8.6;  height, 
6.5;  diameter,  5 mm.  Cat.  No.  207318,  U.S.N.M. 

Station  4425,  off  the  Santa  Barbara  Islands,  California,  in  1,100 
fathoms;  also  off  Cape  San  Martin  in  218  fathoms. 

TINDARIA  RITTERI,  new  species. 

Shell  small,  plump,  smooth  except  for  incremental  lines,  brilliantly 
polished,  pale  olive,  darker  near  the  margin,  rounded  in  front,  inequi- 
ateral,  slightly  recurved,  and  bluntly  pointed  and  attenuated  behind; 
beaks  low,  ligament  very  short  and  wholly  posterior,  1 0 or  1 1 slender 
V-shaped  teeth  on  either  side.  Length,  7;  height,  4;  diameter,  2.6 
mm.,  the  beaks,  2.5  mm.  behind  the  anterior  end.  Cat.  No.  209396, 
U.S.N.M. 

Station  4325,  off  La  Jolla,  California,  in  293  fathoms. 

TINDARIA  DICOFANIA,  new  species. 

Shell  small,  olivaceous,  callistiform,  arcuate,  with  swollen  beaks, 
concentrically  uniformly  sculptured,  nearly  equilateral,  the  anterior 
end  shorter;  a small  lanceolate  lunule  and  escutcheon  present;  both 
ends  rounded,  base  conspicuously  arcuate,  the  posterior  end  slightly 
65008°— Proc.N.M.vol.52— 17 2G 


402 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52  , 


attenuated;  about  11  teeth  on  each  side  of  the  hinge,  the  ligament 
wholly  external.  Length,  4.5;  height,  3.2;  diameter,  2 mm.  Cat. 
No.  215595,  U.S.N.M. 

Station  2923,  off  San  Diego,  California,  in  822  fathoms. 

TINDARIA  CERVOLA,  new  species. 

Shell  small,  thin,  sub  triangular,  of  a uniform  olive  color,  finely 
uniformly  concentrically  sculptured,  with  a few  microscopic  radial 
striulae;  base  conspicuously  arcuate,  dorsal  slopes  nearly  straight, 
the  anterior  slope  shorter,  the  anterior  end  rounded,  the  posterior 
bluntly  pointed,  an  extremely  narrow  and  small  lanceolate  lunule 
and  escutcheon  present;  beaks  conspicuous,  the  prodissoconch  visi- 
ble, whitish;  about  10  anterior  and  14  posterior  teeth,  the  ligament 
small,  wholly  posterior.  Length,  4;  height,  2.7;  diameter,  2 mm. 
Cat.  No.  215594,  U.S.N.M. 

Station  2923,  off  San  Diego,  California,  in  822  fathoms. 

GLYCYMERIS  CORTEZIANA,  new  species. 

Shell  solid,  white  with  a brownish  periostracum,  the  surface  finely 
concentrically  sculptured,  with  less  conspicuous  fine  radiating  striae, 
on  which  the  periostracum  exhibits  ciliated  lines;  valves  moderately 
compressed,  suborbicular,  evenly  rounded  in  front  and  below,  some- 
what produced  behind,  the  lower  margins  finely  crenulated;  beaks 
small,  inconspicuous;  area  very  narrow,  closely  divaricately  grooved; 
hinge  plate  broad,  with  about  12  anterior  and  16  posterior  teeth. 
Length,  22;  height,  20;  diameter,  11  mm.  Cat.  No.  212431,  U.S.N.M, 

Station  2918  on  the  edge  of  Cortez  Bank,  California,  in  67  fathoms. 

GLYCYMERIS  MIGUELIANA,  new  species. 

Shell  solid,  white  with  sparse  zigzag  lines  of  reddish  brown  and  in- 
ternally often  with  a touch  of  brown  near  the  posterior  margin;  sur- 
face smooth  except  for  irregularities  of  growth;  valves  suborbicular^ 
anterior  side  slightly  longer,  posterior  hardly  produced;  beaks  low, 
area  small  and  divaricately  grooved;  inner  basal  margin  crenulated; 
anterior  teeth  10-14,  posterior  9-12;  valves  moderately  convex. 
Length,  23 ; height,  22 ; diameter,  14  mm.  Cat.  No.  120775,  U.S.N.M. 

Station,  San  Miguel  Island,  California. 

LIMOPSIS  SKENIA,  new  species. 

Shell  small,  finely  reticulately  sculptured,  with  a longhaired  vel- 
vetty  periostracum;  narrow,  high,  rather  inflated,  thin,  whitish 
under  the  brown  periostracum;  beaks  small,  area  small,  hinge  line 
short,  with  one  outer  large  and  one  or  two  small  inner  teeth  on  each 
side  of  the  resilifer.  General  form  oblique.  Length,  7 ; height,  9.2 ; 
diameter,  6.5  mm.  Cat.  No.  205883,  U.S.N.M. 


no.  2183.  NEW  NORTHWEST  AMERICAN  BIV ALVES— D ALL. 


403 


Station  4471,  Bowers  Bank,  Bering  Sea,  in  30  fathoms. 

The  peculiar  narrow  oblique  form  is  so  far  unique  in  the  genus.  The 
margins  are  smooth. 

LIMOPSIS  AKUTANICA,  new  species. 

Shell  white,  with  a golden  brown  long-haired  periostracum,  the 
surface  concentrically  somewhat  irregularly  sculptured,  the  ridges 
crossed  by  finer,  closer,  less  conspicuous  striae;  disk  ovate,  compressed, 
with  inconspicuous  beaks,  a very  small  narrow  area  and  a relatively 
large  resilifer;  the  inner  margins  are  flat;  the  hinge  plate  narrow 
with  about  7 posterior  and  9 anterior  teeth;  interior  of  the  disk 
finely  radially  striate.  Length,  21;  height,  18;  diameter,  8 mm. 
Cat.  No.  224263,  U.S.N.M. 

Station  2842,  southeast  of  Akutan  Island,  Aleutians,  in  72  fathoms. 

PTERIA  VIRIDIZONA,  new  species. 

Shell  small,  oval,  translucent,  sea-green,  distributed  in  narrow 
darker  and  lighter  zones,  sculptured  with  narrow,  very  elongate, 
opake,  whitish  scales,  distributed  in  radiating  lines  with  wider  bare 
spaces  between  them;  right  valve  smaller  and  flatter  with  a sinus  for 
the  byssus;  left  valve  larger  with  the  anterior  ear  compressed  but 
not  sinuate;  the  hinge  line  shorter  than  the  shell  with  a shallow 
rounded  sinus  between  the  posterior  ear  and  the  body  of  the  disk; 
interior  with  the  pearly  area  small  and  no  denticulations  on  the  hinge 
line.  Length,  25;  height,  13;  diameter,  5 mm.  Cat.  No.  172600, 
U.S.N.M. 

Long  Beach,  California  (H.  N.  Lowe). 

VULSELLA  PACIFICA,  new  species. 

Shell  small,  irregular,  dark  purple  margined  with  white,  the  sur- 
face sculptured  with  obscure  concentric  ridges  crossed  by  fine  vermic- 
ulate  radial  striations;  interior  dark  purple  with  white  valve 
margins;  resilifer  very  large  and  strong,  inner  valve  margins  smooth. 
Length,  9;  height,  11;  diameter,  about  6 mm.  Cat.  No.  101935, 
U.S.N.M. 

Nicaragua  (Thomas  Bridges). 

The  specimen  may  be  young,  but  it  seemed  worthy  of  description, 
since  no  species  of  this  genus  has  hitherto  been  reported  from  the 
Americas. 


PSEUD AMUSIUM  INCONGRUUM,  new  species. 

Shell  small,  white,  suborbicular,  left  valve  rather  flat  with  short 
straight  hinge  line,  ears  concentrically  scaly,  sculpture  of  disk  con- 
centric continuous  low  sharp  lamellae,  crossed  by  slightly  raised 
radial  lines,  conspicuous  only  at  the  intersections  which  form  in  the 


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PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


middle  of  the  disk  square  reticulations  with  a small  conspicuous 
pustule  at  each  intersection;  laterally  these  are  more  crowded;  right 
valve  concave  near  the  margin,  closely  regularly  concentrically  lam- 
ellose;  anterior  ear  with  five  radial  lines,  coarsely  lamellose  with  a 
shallow  notch  and  serrate  margin.  Height,  14;  breadth,  15;  diam- 
eter, 3 mm.  Cat.  No.  207273,  U.S.N.M. 

Station  2986,  southwest  of  San  Diego,  in  684  fathoms. 

The  sculpture  is  sparser  and  partly  obsolete  near  the  beaks. 

PSEUDAMUSIUM  BISTRIATUM,  new  species. 

Shell  small, suborbicular,  moderately  convex,  white,  thin;  left  valve 
finely  concentrically,  rather  distantly  lamellose,  the  lamellae  closer 
and  more  conspicuous  on  the  subequal  ears;  radial  sculpture  of  very 
fine,  close-set,  uniform  almost  microscopic  elevated  lines,  which  do 
not  reticulate  the  lamella tions;  right  valve  with  the  concentric,  but 
without  the  radial  sculpture,  concave  near  the  margin,  the  disk  about 
as  convex  as  the  other  valve,  ears  subequal,  byssal  notch  short,  acute; 
one  or  two  faint  radii  on  the  ear  above  it.  Height,  7;  breadth,  7; 
diameter,  2 mm.  Cat.  No.  214056,  U.S.N.M. 

Station  2923,  off  San  Diego,  California,  in  822  fathoms. 

LIMATULA  ATTENUATA,  new  species. 

Shell  small,  narrow,  thin,  white,  radially  sculptured  with  low,  rather 
close-set,  rounded  threads,  crossed  near  the  distal  margin  with  low 
concentric  irregular  lamellations  so  as  to  give  that  part  of  the  valve  a 
minutely  scabrous  effect;  the  medial  radii  are  broader  than  the  others 
and  radially  striate,  no  mesial  sulcus  is  noticeable  but  it  is  clearly  indi- 
cated on  the  inside  of  the  valve;  beaks  low,  incurved;  area  triangular, 
resilifer  large  and  excavated;  hinge  margin  short,  strongly  buttressed 
on  each  side;  valve  margin  crenulate.  Height,  7;  width,  3.6;  diam- 
eter, 4 mm.  Cat.  No.  220510,  U.S.N.M. 

Nazan  Bay,  Atka  Island,  Aleutian  chain. 

SEPTIFER  BIFURCATUS,  new  variety,  OBSOLETUS. 

Shell  large,  the  external  sculpture  obsolete,  the  distal  part  of  the 
valves  nearly  smooth.  Cat.  No.  173359,  U.S.N.M. 

San  Diego  Bay,  mud  flats. 

MODIOLUS  (7POLITUS  Verrill  var.)  PALLIDULUS,  new  species. 

Shell  thin,  smooth,  brilliantly  polished,  attenuated  anteriorly,  wide 
and  bluntly  rounded  behind,  divided  into  two  color  areas,  the  dorsal 
large,  translucent  with  a whitish  zigzag  reticulation,  the  ventral 
opaque  white  with  a yellowish  tinge;  hinge  edentulous,  margins 
entire.  Length,  23;  maximum  height,  11.5;  beaks  behind  the 
anterior  end,  1;  diameter,  5 mm.  Cat.  No.  212746,  U.S.N.M. 


no.  2183.  NEW  NORTHWEST  AMERICAN  BIVALVES— D ALL. 


405 


Station  3197,  off  San  Luis  Obispo  Bay,  in  77  fathoms. 

None  of  the  Pacific  specimens  have  the  golden  yellow  color  of  the 
Atlantic  species  and  none  of  them  attain  the  same  size.  Otherwise 
the  shells  are  very  similar. 

DACRYDIUM  PACIFICUM,  new  species. 

Shell  minute,  whitish,  much  the  shape  of  Mus cuius  vernicosus  Mid- 
dendorff,  on  a minute  scale,  differing  from  the  Atlantic  D . vitreum  by 
its  smaller  size  and  more  elongated  outline.  Length,  3.6 ; height,  2.5 ; 
diameter,  1.5  mm.  Cat.  No.  214092,  U.S.N.M. 

Station  3604,  1,401  fathoms,  mud,  in  Bering  Sea. 

MUSCULUS  NIGER  Gray,  new  variety,  OBESUS. 

Shell  resembling  the  typical  flattish  form  but  markedly  more 
inflated.  Length,  60;  height,  31;  diameter,  18  mm.  Cat.  No. 
223317,  U.S.N.M. 

Plover  Bay  near  Bering  Strait,  in  8 to  20  fathoms. 

MUSCULUS  NIGER  Gray,  new  variety,  PROTRACTUS. 

Shell  resembling  the  young  of  the  typical  form  but  more  inflated 
and  elongated,  the  sculpture  very  distinct,  the  medial  area  smooth, 
blackish,  the  dorsal  areas  olivaceous.  Length,  13;  height,  6.5; 
diameter,  5.5  mm.  Cat.  No.  222017,  U.S.N.M. 

North  of  Nunivak  Island,  Bering  Sea,  in  9 fathoms,  gravel. 

MUSCULUS  OLIVACEUS,  new  species. 

Shell  small,  thin,  polished,  pale  olivaceous  near  the  beaks,  growing 
darker  distally;  medial  area  smooth,  anterior  area  with  six  or  seven 
rather  strong  radial  grooves;  posterior  area  with  numerous  shallow 
channeled  radii  crossed  by  rather  regular  slightly  elevated  concentric 
lines,  giving  a silky  luster  to  the  surface;  beaks  inconspicuous, 
inflated;  dorsum  arched,  base  nearly  straight,  both  ends  evenly 
rounded,  the  posterior  slightly  wider;  interior  whitish,  the  margin 
crenulated  by  the  sculpture,  the  beaks  very  close  to  the  posterior  end. 
Length,  10;  height,  6;  diameter,  5 mm.  Cat.  No.  210790,  U.S.N.M. 

Off  Bering  Island,  in  10  fathoms. 

This  differs  in  sculpture,  color,  and  proportions  from  the  young  of 
M.  laevigatus. 

Genus  LITHOPHAGA  Bolten,  1798. 

Section  LABIS  Dali,  1916. 

Type. — Lithophaga  attenuata  Deshay es. 

The  typical  Lithophaga  has  a clean  outer  surface;  Diberus  a divari- 
cate plumose  posterior  incrustation;  Myoforceps , two  crossed  conical 
projections;  the  present  form  has  on  each  valve  a semicylindrical 


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vol.  52. 


smooth  appendage  of  which  the  distal  end  is  internally  flattened  and 
somewhat  separated  from  the  appendage  of  the  opposite  valve,  the 
ends  being  rounded. 


CRENELLA  ROTUNDATA,  new  species. 

Shell  small,  rounded-quadrate,  inflated,  with  a very  thin,  dehiscent, 
pale  olive  periostracum ; beaks  central,  inconspicuous,  with  no  crenu- 
lations  beneath  them;  sculpture  of  faint  incremental  lines  and  obso- 
lete radial  striae  near  the  margin;  inner  margin  very  delicately 
crenulate  except  near  the  beaks.  Length,  4;  breadth,  4;  diameter, 
2 mm.  Cat.  No.  129305,  U.S.N.M. 

Station  2849,  off  Santa  Cruz  Island,  California,  in  155  fathoms, 
sand. 

DERMATOMYA  BUTTONI,  new  species. 

Shell  small,  rounded-quadrate,  plump,  thin,  yellowish  olive,  hardly 
polished,  smooth,  with  iridescent  reflections  from  under  the  perios- 
tracum when  fresh;  beaks  nearly  central,  not  prominent,  hinge  teeth 
normal,  strong;  interior  bluish  white,  margins  entire,  paflial  sinus 
shallow.  Length,  9.8;  breadth,  8;  diameter,  6 mm.  Cat.  No. 
194309,  U.S.N.M. 

Station  3670,  Monterey  Bay,  in  581  fathoms. 

DERMATOMYA  BERINGIANA,  new  species. 

Shell  large,  thin,  plump,  inequilateral,  anterior  end  shorter,  base 
arcuate,  anterior  end  rounded,  posterior  dorsal  slope  first  convexly 
slightly  arcuate,  then  obliquely  sub  truncate  to  meet  the  basal  curve; 
beaks  prominent,  7 mm.  behind  the  anterior  end;  surface  smooth, 
except  for  faint  incremental  irregularities,  iridescent  under  a pale 
olive,  polished  periostracum;  beaks  slightly  prosocoelous, hinge  weak, 
the  teeth  minute,  the  ossiculum  well  developed;  interior  whitish,  the 
pallial  sinus  very  shallow.  Length,  20;  height,  14;  diameter,  12  mm. 
Cat.  No.  205899,  U.S.N.M. 

Bowers  Bank,  Bering  Sea,  in  557  fathoms. 

DERMATOMYA  LEONINA,  new  species. 

Shell  large  for  the  genus,  mactriform,  solid,  inflated,  transverse, 
with  a dull  olivaceous  periostracum,  darker,  and  concentrically 
wrinkled  on  the  posterior  dorsal  area;  surface  smooth  except  for  fine 
incremental  lines  and  microscopic  radial  striulae  often  obsolete; 
beaks  high,  slightly  prosocoelous,  nearly  central;  base  moderately 
arcuate,  anterior  end  rounded,  dorsal  slopes  nearly  straight,  a shallow 
radial  depression  on  the  posterior  dorsal  area,  posterior  end  subtrun- 
cate; hinge  weak,  ligament  deeply  inset;  hinge  teeth  almost  obso- 
lete; margins  entire,  paflial  sinus  shallow,  interior  feebly  iridescent 


NO.  2183. 


NEW  NORTHWEST  AMERICAN  B IV ALVES— D ALL. 


407 


white.  Length,  27;  height,  18.5;  diameter,  14.6  mm.  Cat.  No. 
122564,  U.S.N.M. 

Station  3074,  off  Sea  Lion  Rock,  coast  of  Washington,  in  877 
fathoms. 

CETOCONCHA  MALESPINAE,  new  species. 

Shell  small,  very  thin,  with  prominent  prosocoelous  beaks,  a very 
pale  yellowish  olive  periostracum,  darker  on  the  posterior  dorsal  area; 
in  the  right  valve  is  a strong  radial  ridge  near  the  posterior  hinge  line; 
surface  otherwise  smooth  and  almost  polished  except  for  extremely 
fine  radial  lines  of  minute  granules  only  visible  under  a glass;  shell 
very  similar  to  Isocardia  cor  in  form  and  outline  on  a very  small  scale; 
interior  white,  the  hinge  normal  but  weak.  Length.  12.5;  height,  10; 
diameter,  8.5  mm.  Cat.  No.  212564,  U.S.N.M. 

Station  2859,  southwest  of  Sitka  Bay,  Alaska,  in  1,569  fathoms. 

MYONERA  TILLAMOOKENSIS,  new  species. 

Shell  extremely  thin,  fragile,  inflated,  beaks  nearly  central  (neglect- 
ing the  rostrum),  whitish,  the  anterior  part  of  the  shell  with  about  20 
strong,  rounded,  concentric  ripples  which  cease  posteriorly  at  the 
anterior  border  of  the  radial  sculpture  which  includes  four  strong  and 
about  fifteen  threadlike  radial  riblets  extending  from  the  beaks  to  the 
base,  behind  which  is  a short,  blunt,  concentrically  feebly  striate, 
truncate  rostrum;  base  arcuate,  hinge-line  nearly  straight,  the  right 
margin  slightly  overlapping  the  other.  Length,  18;  height,  12; 
diameter,  10  mm.  Cat.  No.  107819,  U.S.N.M. 

Station  3346,  off  Tillamook  Bay,  Oregon,  in  786  fathoms. 

CUSPIDARIA  APODEMA,  new  species. 

Shell  small,  white,  polished,  swollen,  with  a prominent  tubular 
rostrum;  inequilateral,  the  beaks  6 mm.  behind  the  anterior  end; 
the  rostrum  about  5 mm.  long;  beaks  conspicuous,  prosocoelous; 
the  exterior  smooth  except  for  incremental  lines  and  wrinkles  on  the 
dorsal  side  of  the  rostrum;  hinge-line  nearly  straight,  anterior  end 
rounding  imperceptibly  into  the  semicircular  base  which  is  suddenly 
constricted  at  the  rostrum.  Length,  17;  height,  10;  diameter,  8 mm. 
Cat.  No.  122602,  U.S.N.M. 

Station  2859,  southwest  of  Sitka  Bay,  Alaska,  in  1,569  fathoms. 
Near  but  not  C.  obesa  Loven,  of  the  Atlantic. 

CARDIOMYA  BALBOAE,  new  species. 

Shell  small,  whitish  with  a yellowish  periostracum;  inequilateral, 
rostrate,  somewhat  inflated,  posterior  end  shorter,  anterior  ovately 
rounded;  beaks  small,  pointed,  not  elevated;  sculpture  of  anterior 
half  of  the  disk  faintly  irregularly  concentrically  rippled;  behind 
this  12  to  15  radial,  more  or  less  alternated  threads  extending  to  the 


408 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


margin  from  the  umbones  and  increasing  in  strength  backward;  be- 
hind the  last  and  strongest  an  excavated  concentrically  striated  space 
marks  the  beginning  of  the  rostrum  which  beyond  that  has  four  or  five 
faint  radial  threads  and  is  abruptly  truncate.  Length  8.9;  height,  5; 
diameter,  3.2  mm.  Cat.  No.  208650,  U.S.N.M. 

Station  2911,  on  the  edge  of  Cortez  Bank,  in  60  fathoms. 

CALYPTOGENA  ELONGATA,  new  species. 

Shell  resembling  a Tagelus  in  form,  elongate  compressed,  white 
under  a yellowish  periostracum,  rounded  at  both  ends,  base  nearly 
straight;  anterior  dorsal  slope  short,  beaks  low,  small,  pointed,  about 
10  mm.  from  the  anterior  end  of  the  valves,  posterior  slope  long,  gently 
arcuate;  surface  devoid  of  any  sculpture  except  rather  conspicuous 
incremental  lines;  ligament  strong;  interior  porcellanous  white, 
pallial  line  entire;  hinge  teeth  small,  normal.  Length,  44;  height, 
17.5;  diameter,  10  mm.  Cat.  No.  110774,  U.S.N.M. 

Off  Point  Loma,  California,  in  275  fathoms,  at  station  4432. 

This  can  be  distinguished  at  once  from  the  C.  pacifica  by  its  elongate 
form  and  more  delicate  and  compressed  shell. 

MIODONTISCUS  MERIDIONALIS,  new  species. 

Shell  small,  solid,  white,  with  9 or  10  strong  rounded  adjacent 
radial  ribs  cut  by  about  as  many  concentric  incised  lines,  the  segments 
of  the  ribs  more  or  less  swollen;  beaks  small,  erect,  no  visible  lunule, 
or  escutcheon;  teeth  strong;  inner  basal  margin  coarsely  crenulate. 
Length,  4;  height,  4;  diameter,  2 mm.  Cat.  No.  208948,  U.S.N.M. 

Station  4309,  off  Point  Loma,  California,  in  78  fathoms. 

Smaller,  less  compressed,  and  more  conspicuously  sculptured  than 
the  northern  M.  prolongatus . 

MILNERIA  KELSEYI,  new  species. 

This  species  has  been  confused  from  the  beginning  with  M.  minima 
Dali,  and  is  best  diagnosed  comparatively.  The  latter  has  the  radial 
sculpture,  especially  the  four  strong  ribs  of  the  posterior  part,  coarsely 
and  conspicuously  imbricated,  with  no  very  marked  keel  from  the 
umbo  to  the  posterior  basal  angle.  The  shell  in  a general  way  is  in 
all  respects  less  angular.  M.  Tcelseyi  has  a conspicuous  ridge  extend- 
ing from  the  umbo  to  the  posterior  basal  angle;  the  imbricated  ribs 
are  less  conspicuous,  the  scales  smaller  and  less  prominent,  the  an- 
terior end  more  attenuated,  the  shell  wider  and  more  depressed,  and 
is  apparently  larger  when  mature.  Length,  11;  height,  3;  diameter, 
4.5  mm.  Cat.  No.  253037,  U.S.N.M. 

On  Haliotis  shells,  Central  California. 

M.  minima  has  a rather  large  conspicuous  impressed  lunule  and 
smaller  narrow  escutcheon;  M.  Icelseyi  an  extremely  small  lunule  and 
an  escutcheon  larger  and  more  conspicuous. 


NO.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— DALE. 


409 


THYASIRA  CYGNUS,  new  species. 

Shell  white  with  a pale  straw-colored  periostracum,  moderately 
convex,  sharply  compressed  behind,  the  beaks  prominent,  prosocoe- 
lous  over  a large  cordate  lunule,  the  escutcheon  long  and  very  narrow, 
bounded  by  a sharp  keel;  general  form  rounded  quadrate,  the  com- 
pressed posterior  area  narrow  and  basally  falling  notably  short  of  the 
basal  curve  of  the  disk;  posterior  slope  slightly  convexly  arcuate; 
anterior  distinctly  concave,  meeting  the  basal  arc  in  an  obtuse  angu- 
lation. Length,  14;  height,  13.5;  diameter,  8.5  mm.  Cat.  No. 
222618,  U.S.N.M. 

Station  4224,  Cygnet  Inlet,  Boca  de  Quadra,  Alaska,  in  160  fathoms. 

THYASIRA  TRICARINATA,  new  species. 


Shell  chalky  white,  produced  below,  with  pointed  prosocoelous 
beaks  over  a deeply  impressed  ovate  lunule  bounded  by  a sharp 
carina;  escutcheon  long,  narrow,  lanceolate,  the  valve  margins  rising 
as  a sharp  keel  in  the  middle,  the  outer  border  very  prominently 
keeled,  outside  of  which  is  a similarly  shaped  excavated  area  also 
bordered  by  an  angular  keel;  still  outside  of  this  there  is  a com- 
pressed area  with  no  distinct  anterior  boundary  except  an  obscure  ray 
near  the  umbones ; over  this  area  the  surface  is  concentrically  striated, 
the  rest  of  the  disk  being  nearly  smooth;  hinge  very  feeble,  ligament 
linear.  Length,  15;  height,  18;  diameter,  10  mm.  Cat.  No.  209321, 
U.S.N.M. 


Station  4425,  off  the  Santa  Barbara  Islands,  California,  in  1,100 
fathoms. 


ERYCINA  CATALINAE,  new  species. 


Shell  small,  inequilateral,  the  anterior  side  shorter,  rounded,  the 
base  nearly  straight;  posterior  side  also  rounded,  slightly  attenuated, 
the  dorsal  slope  convex  but  descending;  hinge  strong,  the  teeth  well 
developed;  the  beaks  well  developed,  not  prominent,  the  surface 
smooth  except  for  faint  incremental  lines,  covered  with  a light  yel- 
lowish-brown dull  periostracum.  Length,  2.5;  height,  2;  diameter, 
1.3  mm.  Cat.  No.  210879,  U.  S.N.  M. 

Catalina  Island.  California,  Brannan. 

ERYCINA?  CORONATA,  new  species. 

Shell  small,  white,  rounded  quadrate,  nearly  equilateral,  the  surface 
finely  concentrically  striated;  basal  margin  nearly  straight;  ends 
rounded,  the  posterior  a little  produced  basally,  the  dorsal  slopes 
similar,  slightly  descending,  with  at  each  end  two  to  four  minute  ele- 
vated spinules.  Length,  4;  height,  3;  diameter,  1.2  mm.  Cat.  No. 
225193,  U.S.N.M. 

Off  South  Coronado  Island,  in  3 to  6 fathoms,  Dr.  F.  Baker.  Only 
one  left  valve  was  obtained. 


410 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


VOL.  52. 


ERYCINA  BAKEKI,  new  species. 

Shell  small,  white  with  a pale  yellowish  periostracum,  subquadrate, 
inequilateral,  the  anterior  end  shorter;  hinge  line  short,  straight,  at 
the  outer  extremities  usually  a small  spinule,  beaks  pointed,  the  pro- 
dissoconch  visible;  from  the  beak  extends  a wide  depression  obliquely 
backward  to  the  middle  of  the  base,  becoming  more  defined  distally; 
at  the  base  in  the  adult  it  is  strongly  marked  and  emphasized  by  a 
rounded  sulcus  in  the  margin,  behind  which  the  surface  rises  into  a 
rounded  ridge  armed  with  one  or  more  elevated  short  lamellae,  and 
having  its  basal  termination  produced  into  a sort  of  hook;  hinge 
rather  feeble,  valves  rather  compressed.  Length,  6.3;  height,  4.5; 
diameter,  2 mm.  Cat.  No.  225192,  U.S.N.M. 

Off  South  Coronado  Island,  in  3 to  6 fathoms,  Dr.  F.  Baker. 

This  remarkable  little  shell  doubtless  owes  its  curious  modifica- 
tions to  a commensal  habit  of  living  attached  to  some  other  animal — a 
crustacean  or  annelid. 


ERYCINA  BALLIANA,  new  species. 

Shell  small,  with  the  outline  of  a very  compressed  Kellia , white  with 
a very  pale  yellowish  periostracum,  concentrically  microscopically 
threaded,  the  threads  occasionally  becoming  microscopically  lamellar; 
valves  nearly  equilateral,  the  anterior  part  slightly  longer,  base  evenly 
arcuate,  the  posterior  end  somewhat  attenuated.  Length,  3;  height 
2.9;  diameter,  1.7  mm.  Cat.  No.  225191,  U.S.N.M. 

Off  South  Coronado  Island  in  3 fathoms,  Dr.  F.  Baker.  Named  in 
honor  of  Mrs.  Paula  Ball,  of  the  Conchological  Club  of  Los  Angeles, 
California. 

ERYCINA  CHACEI,  new  species. 

Shell  small,  compressed,  rounded-quadrate;  nearly  equilateral,  the 
anterior  end  slightly  shorter;  beaks  low,  pustular,  minute;  dorsal 
margin  nearly  straight,  basal  margin  gently  arcuate;  surface  finely 
concentrically  striate,  whitish  under  a pale  ashy  periostracum,  both 
ends  nearly  evenly  rounded,  hinge  very  feeble.  Length,  5.3;  height, 
3.5;  diameter,  1.8  mm.  Cat.  No.  211219,  U.S.N.M. 

Station  4343,  off  the  South  Coronado  Island,  in  155  fathoms. 
This  shell  may  eventually  prove  to  be  a Pseudopythina.  Only  one 
right  valve  was  obtained.  It  is  named  in  honor  of  Mr.  and  Mrs.  E.  P. 
Chace,  of  Los  Angeles,  California. 

ERYCINA  SANTAROSAE,  new  species. 

Shell  small,  compressed,  whitish,  with  a thin  pale  brownish  dull 
periostracum;  profile  approaching  E.  balliana  but  more  elongated,  and 
the  surface  smooth,  almost  polished  and  without  the  microscopic  con- 
centric sculpture;  evenly  ovate,  nearly  equilateral,  the  anterior  end  a 


no.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— BALL. 


411 


trifle  shorter;  beaks  low,  pustular,  the  prodissoconch  very  small  but 
distinct.  Length,  4;  height,  3.5;  diameter,  1.5  mm.  Cat.  No. 
194339,  U.S.N.M. 

Santa  Rosa  Island,  California. 

ANISODONTA?  PELLUCID  A,  new  species. 

Shell  minute,  white,  pellucid,  rounded  triangular,  smooth  and 
polished;  beaks  prominent,  dorsal  slopes  convexly  arcuate  behind, 
straighter  in  front;  base  arcuate,  valves  moderately  arcuate  with 
entire  margins;  hinge  with  developed  anterior  and  posterior  laterals 
and  two  cardinals,  the  anterior  tooth  bifid.  Length,  2.3;  height,  2; 
diameter,  1.3  mm.  Cat.  No.  208475,  U.S.N.M. 

Monterey  Bay,  California. 

The  generic  place  of  this  minute  shell  is  doubtful,  but  the  form  is 
distinctly  like  Eucharis,  though  the  hinge  appears  to  differ. 

ROCHEFORTIA  FERRUGINOSA,  new  species. 

Shell  small,  white,  thin,  subdonaciform,  compressed,  invariably 
coated  with  a ferruginous  layer  like  some  species  of  Axinulus , inequi- 
lateral ; anterior  side  longer,  apical  angle  about  90 ; both  ends  rounded 
base  arcuate.  Length,  4.5;  height,  3.25;  diameter,  1.5mm.  Cat.  No. 
214413,  U.S.N.M. 

San  Francisco  Bay. 

ROCHEFORTIA  BERINGENSIS,  new  species. 

Shell  large  for  the  genus,  oval,  white  with  an  olivaceous  periostra- 
cum,  thin,  somewhat  compressed,  sculptured  rudely  with  low  irregu- 
lar concentric  ridges ; inequilateral,  posterior  end  longer,  both  rounded ; 
beaks  not  prominent,  hinge  small  and  feeble,  except  that  the  resilium 
and  its  attachments  are  rather  large.  Length,  11.5;  height,  10; 
diameter,  4 mm.  Cat.  No.  210951,  U.S.N.M. 

Bering  Island,  Bering  Sea  (Grebnitzsky). 

ROCHEFORTIA  GREBNITZSKII,  new  species. 

% 

Shell  small,  translucent,  polished,  whitish;  nearly  equilateral; 
general  shape  that  of  Bornia,  but  without  the  brilliant  surface;  sculp- 
ture of  fine  concentric  lines  visible  under  a glass,  which  render  the 
surface  dull;  beaks  rather  prominent,  hinge  weak.  Length,  3.25; 
height,  2.5;  diameter,  1.3  mm.  Cat.  No.  207258  a,  U.S.N.M. 

Bering  Island,  Bering  Sea  (Grebnitzsky). 

This  may  ultimately  prove  to  be  a Bornia. 

ROCHEFORTIA  GOLISCHI,  new  species. 

Shell  subquadrate,  compressed,  thin,  white,  very  inequilateral; 
the  anterior  end  very  short,  beaks  low,  1 mm.  behind  the  anterior 


412 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


end;  posterior  end  rounded  almost  exactly  like  the  anterior,  base 
gently  arcuate;  surface  polished,  minutely  concentrically  rippled; 
prodissoconch  visible;  hinge  weak,  the  resilifer  large,  obliquely  in- 
clined backward.  Length,  6;  height,  5.5;  diameter,  2.5  mm. 
Cat.  No.  210876,  U.S.N.M. 

Station  2900,  off  Santa  Rosa  Island,  California,  in  13  fathoms. 
Named  in  honor  of  Mr.  W.  H.  Golisch,  of  the  Los  Angeles  Concholog- 
ical  Club. 

PSEUDOPYTHINA  MYACIFORMIS,  new  species. 

Shell  small,  myaciform,  plump,  nearly  equilateral,  the  posterior 
end  slightly  shorter,  wider,  and  rounded;  anterior  end  more  atten- 
uated; surface  finely  concentrically  threaded,  but  obscured  by  an 
habitual  coating  of  a blackish  color,  probably  manganese  dioxide; 
the  shell  underneath  it  is  yellowish  white;  hinge  weak,  the  ligament 
carrying  a long,  very  narrow,  lithodesma.  Length,  8.5;  height,  5.5; 
diameter,  3 mm.  Cat.  No.  133235,  U.S.N.M. 

Port  Orchard,  Puget  Sound.  The  young  shells  are  proportionately 
shorter. 

TR1GONIOCARDIA  EUDOXIA,  new  species. 

Shell  small,  mottled  with  lighter  and  darker  rose-color,  suborbicular, 
inflated,  strongly  sculptured;  radial  sculpture  of  15  sharp  angular 
ribs  with  subequal  interspaces,  the  keel  of  the  ribs  sparsely,  regularly, 
minutely  pustular;  on  the  posterior  dorsal  area  are  six  additional 
smaller  more  closely  pustular  riblets ; the  interspaces  in  all  are  finely 
concentrically  rugose;  the  hinge  is  strong;  the  interior  margins 
deeply  sulcate  in  harmony  with  the  radial  sculpture;  the  central  part 
of  the  interior  is  whitish.  Length,  9;  height,  9;  diameter,  8 mm. 
Cat.  No.  208590,  U.S.N.M. 

Station  3020,  Gulf  of  California,  in  7 fathoms. 

PROTOCARDIA  PAZIANA,  new  species. 

Shell  small  and  delicate,  resembling  P . panamensis  Dali,  but  smaller, 
more  delicate,  more  elongated,  and  with  the  spinose  posterior  sculp- 
ture much  more  prominent  when  preserved  intact;  sculpture  of  about 
40  anterior  minutely  nodulous  ribs,  each  giving  the  effect  of  a string 
of  beads,  and  to  the  interspaces  of  punctation;  there  are  about  22 
ribs  on  the  posterior  area,  which,  when  intact,  carry  close-set  spinules; 
the  inner  margins  are  sharply  serrate ; the  hinge  margin  near  the  um- 
bones  has  a tinge  of  crimson,  otherwise  the  shell  is  yellowish  white. 
Length,  10;  height,  8.6;  diameter,  6 mm.  Cat.  No.  211618,  U.S.N.M. 

Station  2828,  off  La  Paz,  Gulf  of  California,  in  10  fathoms. 

CARDIUM  DULCINEA,  new  species. 

Shell  obliquely  ovate,  strongly  radially  sculptured  with  about  22 
rounded  ribs  with  narrower  not  channeled  interspaces;  the  more 


NO.  2183. 


NEW  NORTHWEST  AMERICAN  BIV ALVES— D ALL. 


413 


anterior  ribs  are  flattened;  between  the  last  six  in  the  narrow  inter- 
spaces is  a minute  undulation  which  becomes  obsolete  as  the  shell 
grows;  the  color  of  the  shell  is  ivory  white,  more  or  less  concentrically 
mottled  with  reddish  brown;  interior  white,  channeled  in  harmony 
with  the  radial  sculpture,  the  margins,  especially  behind,  deeply  sul- 
cate;  beaks  prominent,  conspicuously  incurved.  Length,  43;  height, 
52;  diameter,  36  mm.  Cat.  No.  193824,  U.S.N.M. 

Real  Llejos,  Gulf  of  Dulce,  Central  America. 

SAXIDOMUS  GIGANTEUS  Deshayes,  1839. 

New  variety  brevis.  Shell  short,  subtriangular,  small  in  comparison 
with  type  and  much  less  elongated.  Length,  60;  height,  50;  diam- 
eter, 33  mm.  Cat.  No.  204020,  U.S.N.M. 

Mole  Harbor,  Admiralty  Islands,  Alaska,  Mrs.  Stephens. 

PROTOTHACA  STAMINEA,  new  variety  SPATIOSA. 

Shell  large,  heavy,  rounded  quadrate,  inequilateral,  the  beak  be- 
hind the  anterior  end  18  mm.;  yellowish  or  brownish  white  without 
markings;  sculpture  of  simple,  similar,  narrow  radial  ribs  with  nar- 
rower interspaces,  except  on  the  posterior  dorsal  area  where  there 
are  a few  wider  ribs  with  deeper  interspaces;  inner  margins  finely 
crenulate;  pallial  sinus  deep,  narrow,  nearly  horizontal.  Length, 
80;  height,  67;  diameter,  50  mm.  Cat.  No.  151562,  U.S.N.M. 

Coos  Bay,  Oregon,  Dali. 

PSEPHIDIA  BRUNNEA,  new  species. 

Shell  small,  rounded  triangular,  moderately  convex,  brown,  pale 
yellow  with  zigzag  brown  reticulation,  or  even  pale  yellowish  with 
only  traces  of  red  or  brown  on  the  hingeline;  surface  apparently 
smooth,  with  a dull  silky  effect,  which  on  magnification  is  seen  to  be 
due  to  minute  concentric  close-set  threadlike  sculpture;  beaks  promi- 
nent, prodissoconch  minute  but  distinct;  hinge  normal,  strong; 
inner  margins  entire,  pallial  sinus  shallow,  irregular.  Length,  3.7; 
height,  3;  diameter,  2 mm.  Cat.  No.  109469,  U.S.N.M. 

Catalina  Island,  California,  in  16  fathoms,  Dali. 

The  shells  are  often  crowded  with  nepionic  young  as  in  Sphaerium. 

MACOMA  BROTA,  new  name. 

This  is  TeTlina  edentula  Broderip  and  Sowerby,  1829,  not  of  Speng- 
ler,  1793;  and  in  part  T.  lata  of  Middendorff,  1851,  not  of  Gmelin, 
1792. 

The  following  form  would  seem  to  be  specifically  distinct  were  there 
not  a few  intermediate  specimens: 


414 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


MACOMA  BROTA,  new  variety,  LIPARA. 

Shell  resembling  brota  but  more  rotund,  less  rostrate,  with  a wider 
and  rounder  anterior  end,  shorter  and  more  rounded  posterior  end, 
and  more  polished  surface.  The  respective  measurements  are  as 
follows,  in  millimeters:  219,461;  M.  brota:  Height,  53;  length,  74; 
diameter,  22;  posterior  end,  32.  223,032;  M.  lipara:  Height,  57; 

length,  74;  diameter,  25;  posterior  end,  33.  Cat.  No.  223032, 
U.S.N.M. 

Both  have  the  same  distribution  south  of  Bering  Strait,  but  I have 
not  seen  lipara  from  Arctic  waters.  Both  reach  Puget  Sound. 

MACOMA  INQUINATA  Deshayes,  1854. 

New  variety  arnheimi.  Shell  resembling  the  typical  inquinata  but 
shorter,  and  relatively  more  plump;  the  beaks  15  mm.  behind  the 
anterior  end;  the  basal  margin  somewhat  produced;  the  rostra tion 
shorter,  less  pronounced  and  less  obliquely  twisted.  Length,  38; 
height,  30;  diameter,  15  mm.  Cat.  No.  122537,  U.S.N.M. 

Kodiak  Island,  Alaska,  Arnheim. 

MACOMA  QUADRANA,  new  species. 

Shell  small,  white,  polished,  intermediate  between  M.  carlottensis 
Whiteaves,  and  M.  inflatula  Dali,  but  smaller  than  either;  perios- 
tracum  pale  straw  color,  slightly  iridescent,  microscopically  concen- 
trically striated;  anterior  end  larger,  posterior  end  short,  obliquely 
sub  truncate,  the  rostrum  slightly  bent  to  the  right;  the  right  valve  a 
little  flatter  than  the  left;  two  faint  low  riblets  extending  from  the 
beaks  to  the  posterior  basal  angle ; hinge  very  weak,  pallial  sinus  deep 
and  high.  Length,  19;  height,  13.5;  diameter,  7 mm.  Cat.  No. 
225421,  U.S.N.M. 

Boca  de  Quadra,  Alaska.  Type-specimens  from  off  Point  Concep- 
tion at  station  2892,  in  284  fathoms 

MACOMA  TRUNCARIA,  new  species. 

Shell  small,  subquadrate,  white,  nearly  equilateral,  the  posterior 
end  slightly  shorter,  attenuated  sub  truncate;  basal  margin  nearly 
straight,  anterior  end  evenly  rounded,  beaks  not  prominent,  dorsal 
slopes  subequal,  the  posterior  steepest;  sculpture  only  of  incremental 
lines  irregularly  prominent;  hinge  teeth  feeble;  interior  chalky  white, 
the  pallial  sinus  reaching  only  to  the  vertical  of  the  beak,  rounded, 
free  from  the  pallial  line.  Length,  15;  height,  10;  diameter,  4 mm. 
Cat.  No.  210916,  U.S.N.M. 

Arctic  coast  between  Cape  Halkett  and  Garry  River. 

ERVILIA  CALIFORNICA,  new  species. 

Shell  small,  ovate,  white  with  a rosy  flush,  inequilateral,  the  pos- 
terior end  shorter;  the  beaks  inconspicuous,  the  ends  rounded,  the 


NO.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— DALE. 


415 


basal  margin  arcuate;  sculpture  of  fine  close-set  regular,  uniform 
concentric  threads  over  the  whole  surface;  hinge  strong,  pallial  sinus 
small.  Length,  7;  height,  4.5;  diameter,  2 mm.  Cat.  No.  151419, 
U.S.N.M. 

San  Pedro,  California,  Bridwell. 

MACTRELLA  CLISIA,  Dali,  1915. 

Shell  large,  white,  with  a thin,  dehiscent  periostracum,  conspicu- 
ously arcuate,  inflated,  and  egregiously  keeled  around  the  posterior 
dorsal  slope;  anterior  end  produced,  attenuated,  rounded;  beaks 
very  high,  notably  prosocoelous ; posterior  slope  sharp,  posterior  end 
flattened,  the  flat  area  bordered  with  a high  keel,  in  front  of  which  is  a 
marked  constriction;  the  flat  area  is  divided  by  an  elevated  ray  into 
two  nearly  equal  parts  which  are  somewhat  excavated ; the  valve  mar- 
gins near  the  beaks  prominently  produced;  sculpture  only  of  lines  of 
growth  which  are  fairly  conspicuous;  hinge  line  extremely  short, 
pallial  sinus  reaching  only  to  the  vertical  from  the  posterior  lateral 
teeth,  the  posterior  end  with  an  oval  gape.  Length,  88;  height,  66; 
diameter,  32  mm.  Cat.  No.  271481,  U.S.N.M. 

Type  from  Manzanillo,  Mexico.  Range  thence  to  Santa  Elena, 
Ecuador. 

This  remarkable  shell  is  more  like  the  West  Indian  species  than  it 
is  to  M.  exoleta  of  the  Pacific  coast,  but  all  its  characters  are,  as  it 
were,  exaggerated  to  a fantastic  extent. 

SPHENIA  TRUNCULUS,  new  species. 

Shell  short,  whitish  with  a dirty  ash-colored  periostracum,  rude  and 
more  or  less  distorted,  abruptly  truncate,  almost  equilateral,  the 
anterior  portion  swollen,  the  posterior  part  attenuated.  Length,  7; 
height,  4.3;  diameter,  4 mm.  Cat.  No.  160116,  U.S.N.M. 

San  Diego,  California,  among  barnacles  on  the  wharf  piles. 

SPHENIA  PHOLADIDEA,  new  species. 

Shell  small,  thin,  white,  with  a blackish  periostracum,  which  is  con- 
spicuously laminate  on  the  posterior  dorsal  area;  very  inequilateral, 
the  anterior  side  shorter,  the  beaks  inconspicuous,  4 mm.  behind  the 
anterior  end;  sculpture  of  rude  incremental  lines,  posterior  end 
abruptly  truncate,  hardly  attenuated;  pallial  sinus  rounded,  not 
reaching  the  vertical  of  the  beaks;  hinge  with  a prominent  toothlike 
projection  in  the  right  valve  before,  in  the  left  valve  behind  the  resi- 
lifer.  Length,  12;  height,  5.3;  diameter,  4 mm.  Cat.  No.  2581, 
U.S.N.M. 

Santa  Barbara,  California,  Major  Rich. 

CORBULA  PORCELLA,  new  species. 

Shell  small,  ashy  white,  inequivalve,  the  left  valve  smaller;  inequi- 
lateral, the  posterior  end  larger;  rounded  in  front,  pointed  behind; 


41G 


PROCEEDINGS  OF  THE  NATIONAL  MUSEUM. 


vol.  52. 


a prominent  angle  separates  the  posterior  dorsal  area  from  the  rest  of 
the  disk;  surface  concentrically  evenly  threaded,  the  threads  a little 
more  pronounced  on  the  dorsal  area;  an  obscure  almost  microscopic 
radial  striation  is  sometimes  apparent;  the  siphons  protrude  beyond 
the  rostrum  with  a dense  covering  of  wrinkled  periostracum ; interior 
white,  hinge  normal,  the  basal  margin  of  the  right  valve  partly  over- 
lapping that  of  the  left  valve;  pallial  sinus  obsolete.  Length,  8.5; 
height,  4;  diameter  4.5  mm.,  but  the  shell  is  often  larger.  Cat.  No. 
97039,  U.S.N.M. 

Station  2838,  off  Lower  California,  in  44  fathoms,  mud.  The  spe- 
cies extends  northward  to  the  Santa  Barbara  Islands,  California. 

CORBULA  KELSEYI,  new  species. 

Shell  rather  large,  rounded  triangular,  whitish,  heavy,  not  inflated ; 
the  surface  sculptured  by  low  concentric  lamellae,  a little  more  promi- 
nent near  the  posterior  end  of  the  shell,  separated  by  equal  or  slightly 
wider  interspaces  crossed  by  fine  radial  threads  which  do  not  crenu- 
late  the  lamellae;  there  is  no  defined  posterior  dorsal  area  or  keel; 
interior  with  a deep  anteriorly  rounded  pallial  sinus,  fused  with  the 
pallial  line  below  for  the  greater  part  of  its  length.  There  seems  to 
be  a small  narrow  lunular  area  in  the  left  valve.  Length,  16;  height, 
10;  diameter  of  left  valve,  3 mm.  Cat.  No.  120691,  U.S.N.M. 

Catalina  Island,  California. 

Named  in  honor  of  Prof.  F.  W.  Kelsey  of  San  Diego. 

PANOMYA  ARCTICA  Lamarck,  new  variety,  TURGIDA. 

Shell  very  similar*  to  the  North  Atlantic  form  but  very  much  more 
capacious  and  larger.  Length,  90;  height,  60;  diameter,  48  mm. 
Cat.  No.  151224,  U.S.N.M. 

This  form  is  common  to  the  Aleutian  Islands,  and  eastward  as  far 
as  the  Shumagins.  The  type-specimen  is  from  Popoff  Strait  in  the 
Shumagin  group,  Alaska. 

PANOMYA  BERINGIANA,  new  species. 

Shell  resembling  P.  arctica  Lamarck,  in  a general  way,  but  thinner, 
less  cylindrical,  much  larger,  and  proportionately  shorter.  Length, 
130;  height,  80;  diameter,  50  mm.  A single  valve  reaches  a length 
of  150  and  a height  of  110  mm.  Type-snecimen,  Cat.  No.  212875. 
U.S.N.M. 

Station  3529,  near  the  Pribiloff  Islands,  in  56  fathoms.  Eastern 
Bering  Sea  in  general. 

SAXICA VELLA  PACIFICA,  new  species. 

Shell  small,  thin,  white,  with  a pale  olive  dehiscent  periostracum  ; 
inequilateral,  the  anterior  end  shorter  and  more  attenuated,  the  pos- 
terior longer,  more  vertically  expanded;  surface  sculptured  only  by 


NO.  2183. 


NEW  NORTHWEST  AMERICAN  BIVALVES— HALL. 


417 


incremental  lines;  a rounded  ridge  extends  from  the  inconspicuous 
beak  to  the  posterior  basal  margin,  but  there  is  no  keel  or  angle;  in- 
terior distinctly  pearly,  hinge  as  in  the  Atlantic  species.  Length, 
5.8;  height,  3;  diameter,  2 mm.  Cat.  No.  209912,  U.S.N.M. 

Station  4356,  131  fathoms,  off  Point  Loma,  San  Diego  County, 
California. 

PHOLADIDEA  SAGITTA  (Stearns  Ms.). 

Shell  closely  similar  to  P.  penita  Conrad,  but  with  shorter  propor- 
tions, measured  longitudinally,  and  with  a corresponding  widening 
of  the  dorsal  appendages  of  the  adult.  In  all  other  respects  it  resem- 
bles P.  penita , of  which  it  is  doubtless  a variety.  The  name  having 
found  its  way  into  collections,  it  was  thought  best  to  give  it  an  ac- 
knowledgable  status.  The  type-specimen  comes  from  Monterey, 
California.  Cat.  No.  63312,  U.S.N.M. 

65008° — Proc.N.M.vol.52 — 17 27 


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